Marine Planning

Marine Planning

The planning of the offshore, marine environment on the Severn is relatively recent, compared with planning on land. Following significant legislation in 2009, marine planning was brought in to aid the sustainable use of our coasts and seas through managing and balancing the activities.

Marine planning follows a similar approach to terrestrial planning – setting the direction for decision making at a local level. Marine plans are used by public authorities as part of the decision-making process for all new activities and developments affecting the marine area.

There are two plans for the Severn Estuary, the South West Marine Plan and the Welsh National Marine Plan. As the Severn Estuary is a cross-border site, activities should consider both the Welsh Government and the Marine Management Organisation (MMO) and their marine plans. Working together the MMO and Welsh Government have produced The Severn Estuary: cross-border marine planning guide, which provides an overview of marine planning policies relevant to the Severn Estuary.

Take a look at the animation below for more about Marine Planning in the Severn Estuary, specifically in reference to the South West Marine Plan in England and what this means for a cross-border area.

Marine planning:

  • Guides marine users to the most suitable locations for different activities.
  • Manages the use of marine resources to ensure sustainable levels.
  • Works with all marine users to ensure everyone has an opportunity to contribute to marine plans.
  • Takes a holistic approach to decision making and consider all the benefits and impacts of current and future activities that occur in our marine environment.


The Severn Estuary is one of the largest estuaries in Britain and has the second highest tidal range in the world.

Marine Planning EnglandMarine Planning Wales
The Marine Management Organisation (MMO) published the South West Marine Plan in 2021. The south west inshore marine plan area covers an area of approximately 2,000 kilometres of coastline stretching from the River Severn border with Wales to the River Dart in Devon, taking in a total of approximately 16,000 square kilometres of sea. Wales, and its marine area, and the south inshore marine plan area border the south west inshore marine plan area.

The south west offshore marine plan area includes the area from 12 nautical miles extending out to the seaward limit of the Exclusive Economic Zone, a total of approximately 68,000 square kilometres of sea. The marine areas of Wales, France, Ireland, Guernsey and the south offshore marine plan area border the south west offshore marine plan area. The South West Marine Plan provides a policy framework which will be used to help inform decision-making on what activities take place in the marine environment and how the marine environment is developed, protected and improved in the next 20 years. It provides a clear, evidence-based approach to inform decision-making by marine users and regulators on where, when or how activities might take place within the south west marine area, balancing environmental, economic and social factors.

You can view all the Marine Plan Areas in England here.
Welsh Government published the first Welsh National Marine Plan (WNMP) in November 2019. It sets out Welsh Government’s policy for the next 20 years for the sustainable use of Wales’ seas. In contrast to the English marine plans, the Welsh National Marine Plan is not currently split into regional areas, and therefore, Welsh Ministers are the planning authority for the Welsh:

• Inshore region (out to 12 nautical miles)
• Offshore region (12 to 200 nautical miles)

The WNMP contains plans and policies for both the inshore and offshore regions. It aims to:
• Support the vision for clean, healthy, safe and diverse seas.
• Guide future sustainable development.
• Support the growth of marine space and natural resources or blue growth.

Implementation guidance has also been published to help authorities understand the decisions they will need to take. There are a series of useful resources on the Welsh Government website about the Marine Plan, including webinars, an animation and infographics.

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